Apparatus for boring through earth formations

ABSTRACT

An apparatus for, and a method of, boring through earth formations, employing a drill bit which comprises a rotary drill, in combination with a device for producing pulsed jets of liquid under high pressure. The device is arranged to cut and fracture the bottom periphery of the borehole and the drill bit cuts and fractures the bottom of the borehole.

United States Patent im wi Hall et al. (451 Aug. 5, 1975 [54] APPARATUS FOR BORING THROUGH www :mm atm-n mm2 x EARTH FORIWATIQNS hltl ,l llfl'fl Elmore et Lil. X ).ti-lti ZlV/ Miller et ilu ITS/422 X [75] Inventors: J. Michael Hall. Annapolis. Md.; 3.7mm] 1,1197@ Hull ci m1 239,'102

Louis L. Clipp, McLean. Vil .lsllll H1974 (`oole 239]]01 ullllil'i H1974 Tiivlor et Lil, 23g/IUI X [73] Assignee; hxotech, Incorporated,

G'Liithersburg. Md, li'lmill'y lfiumillcr-David H. Brown ll Flled Oftl8- |973 .Alf/mwa), fgwzi. nr Firm-Morton, Bernard, Brown` [2|] Appl- NO 4071484 Rtilierts L Sutherland [52 U.S. Cl. 17E/93; 175.1"422', Zlfltll {57} ABSTRACT [5l] Int. Cl Btlh BJI-MEZlh NIH Y y [is] Field ofsearch 1751421916165; www@ l md ,.melmd .Of 50"?? hmugh www m1 erirth lormeitions. employng u drill bit which Comprises ai rotary drill` in combination with i device for produeiny pulsed jets of liquid Linder high pressure. [56] A Referer??? ('ld The device is urr'einged to eut und fracture the bottom UNITED STAIhS PATENIS periplier) of the borehole rind the drill hit euts und BJ Iltl() lflQbB Boho,..... with? frnetures the bottom of the borehole.

3.346.058 10H96? Bouyoueos... ITS/'56 3.363.706 111968 Feenstra. lul X 2 Claims` 2 Drawing Figures i, e 15| hlll i i i l i |2e\;- i y ize/ l l .l l

so l |40 SHEET PATENTE() AUB 51975 1 APPARATUS FOR BORING THROUGH EARTH FORMATIONS The present invention pertains to an apparatus for anda method ot' employing pulsed iets of liquid for bor ing through earth formationsY More particularly, this invention relates to a drill bit comprising a rotary drill means and a source of high pressure, high velocity` pulsed jets of liquid to cut and fracture rock at. the periphery of the borehole and to the use of such drill bits.

ln the past, oil wells have been bored into the earth by means of various different types of drill bits which are rotated to mechanically bore downwardly into the earth. These bits are usuallyprovided with small open ings or passages therein which terminate rearwardly of the mechanical cutting edges. Drilling mud or air under pressure is usually directed through these passages so that the material cut away is eventually washed or blown upwardly and remove from the bored hole, Most of the various types of present conventional drill bits mechanically bore into the earth to loosen the material which is subsequently washed upwardly by means of the drilling fluid which is forced through the passages lwhich terminate rearwardly ofthe mechanical cutting edges [n boring wells into the earth, rock formations are frequently encountered which are extremely hard and which slow the drilling even with the most modern rotary drill equipment. Also, when drilling through earth formations, the usual rotary drill bits demonstrate greater wear on that portion of the cutting bit near the bottom periphery of the borehole. The rate of wear on such periphery has been found to be more pronounced when a gas is circulated to remove cuttings than when a liquid, eg., drilling mud, is so used. Accordingly, there have developed rotary drills which employ a conv tinuous stream of a liquid directed towards the bottoni ofthe borehole to assist in removing the rock. One such apparatus is disclosed in Pat. No. 3,112,1'400, which shows a device employing a gas, or liquid under :.l pressure of 2500 to 20,000 psi to assist a rotary drill in boring through rock formations. Such apparatus of the prior art has not proven to be entirely satisfactory, however, because the continuous, relatively low presY sure liquid stream does not provide for cutting and fracturing ofthe rock, Often solids are suspended in the pressure fluid with the intention of increasing the effectiveness with which the fluid stream cuts the rock', how ever, this has been found to create new problems, since such materials tend to abrade conduits in the drilling apparatus through which they pass and since the mate rials are particularly damaging to the rio/*yles which are required to impart velocity to the stream of tluid.

The apparatus and method of the present invention overcomes these disadvantages and employs` a drill bit which comprises the combination ol`a rotary drilling bit with means for rapidly supplying pulsed iets oi' high pressure liquid to cut and fracture the borehole bottoni peripheral surface. The pulsed jets of liquid are rapidly expelled sequentially. eg., up to or 30 a second. at high velocity and with a stagnation pressure in excess of 50,000 psi, preferably' in excess of 100,000 psi. and even more preferably in excess o1`300.0|l0 psi. and are directed to the bottom surface ofthe borehole, usually to the periphery or outer extremity, ie., "lscrf". of the bottom surface where the bottoni surface mates with the borehole sidewall, but sometimes at other locations on the bottom surface as welt. to form a cutout ring on that bottoni surface [his arca ofthe bottoni surface, including not only the bottom surface periphery or outer extremity but also a portion ofthe bottom surface and boreholc sidewall itself, both adjacent such extremity, is the more difficult area for a typical drill to cut and is referred to in this specification and the claims as the "kerf or "bottom peripheral surface" ot the borehole. The pulsed iets o1` liquid serve to cut and fracture the bottoni peripheral surface in the borehole and the rotary drill serves to cut and fracture the bottom surface. `l`hei'eby, tht` hl`e ofthe rotary drill bit is extended signiiicantly. often by a factor of about three times or more.

The present invention is described in further detail with reference to the drawing in which;

F10. l illustrates a fragmentary sectional view of the apparatus of this invention showing the drill positioned at the bottoni of a borehole;

FlG. 2 illustrates in detail a preferred embodiment of the apparatus for producing the pulsed iets with the rotary drill shown in phantom.

ln 1"l(i. l, drill bit l1() is shown positioned in bore hole 111 to drill through the earth. The dericlt. draw works, drill stem. etc., which are conventional, are now shown. Drill bit 111) includes a rotary drill bit support 114 which. for example, has a plurality of essentially equally spaced support arms 116 depending therefrom, Each support arm 116 has extending therefrom a bit axis 118. which, in turn. has rotatably mounted thereon :l rotary conical drilling bit 121). retained on bit axis 1 I8 by bearings 122.

Rotary drill hit support 114 is threadably attached to casing |24. (lising 12.4. in turn, is threadably con nccted to drill stem 12h. Drill stem 126 transmits rotary motion through drill bit support 114 to drill bit Il() in a conventional manner to effect fracturing of the earth formation ,it the bottoni ofthe borehole luch drill bit is rotated on its bit uis 118 by suitable drive means, as is well known in the art, causing fracturing of earth formation 112. lltiid supply bore 128 passes longitudinally through drill stem 12b and casing 124 and then through rotary drill hit support 114, support arm 116 and bit isis 112i. At the tip of bits airis |18, no/Yle 134 is proyidcd to direct fluid from supply bore 128 against the interior of conical drilling bit 12() to cod drilling bit 1Z0 and bearings 122 and to clean particlcs tbercfronr lhe fluid passes from conical drilling bit 120 through annular' gap 136 and to the bottom of tru` lioilfhole. Furth, chipped particles ol`roc1t and the like, can be carried by thc Huid, if desired. from the bottom of borehole 111 upwards in annular gap 137 bctwcen drill stein 12h and the borehole wall 112.

lhc device for creating pulsed iets of liquid is scheY rnntically shoun and includes no/rle block 138, which fits snugly within casing 12.4 and is retained in such position by rotary drill bit support 114 liston 141) is also mounted in casing 124, which, together with drill stem 126. provides for limited movement of the piston, (hamlier 142 is formed in no/zle block 138 with piston 14() proyidingl the upper surface and nozzle 144 is at4 [ached to the bottom of chamber 142. No/,rle |44 is mounted so that it is directed lisce arrows 146i toward the keriV 148 :il thc borchcolc bottom surface. A hamrncr 1511 is proyidcd .ihoyc piston 140. Hammer 150 is acted upon by a force lsec arrow 151) to drive the hammer against piston 140. When hammer IS) strikes piston 140,11 driws piston down and forces water,

or other liquid. from chamber 142 out nozzle 144 as a pulsed jet. Water is supplied to chamber 142 through line 152, check valve 154 and line 156.

ln operation, the drill bit 110 is actuated and operated in a conventional manner and drilling fluid is supplied through line 128 to remove chips from bit 120. The action of the drill bit upon the borehole is, however, dramatically changed, since the drill bit no longer acts upon the kerf but only upon the center of the borehole bottom surface. Pulsed water jets are created and passed through nozle 144 to cut away at the kerf. These water jets are created using the device schematically shown in FIG. l, which may be, for example, one of the devices for creating pulsed jets shown in greater detail in US. Pat. applications, Ser. Nos. 407,496, (now U.S. Pat. No. 3,841,159) and 407,485, filed concurrently herewith by J. Michael Hall and Louis L. Clipp. Fluid from line 128 can be used as the operating force for hammer 150. FlG. 2 shows in detail a preferred em bodiment of the device for producing pulsed jets.

ln the embodiment of FIG. 2, drill bit 210 is shown schematically with details of the device for producing pulsed liquid jets. ln operation of the device, water is supplied to chamber 242 from the surface through line 252, check valve 254 and line 256. This water is acted upon by piston 240, actuated by hammer 250 to force the liquid through nozzle 244 in the form of a pulsed jet. Piston 240 is slidable within casing 224 and a compressed air spring 241 is provided between piston 240 and the lower end 224' of casing 224 so that the piston is normally biased to its upper position, Seals and bushings (not numbered) are shown. Spring 241 may, if desired, be a mechanical spring.

The device is shown in FIG. 2 in the mode it would be ifa pulsed jet has just been produced. lri this mode. piston 240 and hammer 250 are in a first position. In order to render the device capable of producing another pulsed jet. compressed air. supplied from the surface through the interior ofthe drill stern 226 to a central manifold 227 securely mounted within drill Stem 226 by plate 229. passes through opening 223 and eonduit 221 to act upon the upper surface 240' of piston 240 and force piston 250 in the upward direction. Piston 250 is slidable along the central manifold 227. Also. as the compressed air passes through manifold 227, discharge opening 223 and line 221 to move hammer 250 upward. spring 241 moves piston 240 upward. Once hammer 250 has been moved off piston 240, the compressed air is free to move through line 300 and act upon shuttle cock 302, which is slidable within chamber 304 and move shuttle cock 302 to the right. thereby' closing chamber 242 from communication with nozzle 244. As hammer 250 continues to move upward, however. communication between manifold 227 and line 221 through opening 223 is discontinued, At this point. or slightly thereafter, the continued movement of piston 250 connects discharge opening 22S and line 231 with manifold 227, so that the compressed air is supplied between plate 229 and piston 250 to force piston 250 downward. At the same time, compressed air is supplied through line 306 to chamber 304. where it acts upon shuttle cock 302 to move the shuttle cock to the left and provide communication between chamber 242 and nozzle 244. The size ofthe piston and hammer and the pressure ofthe air are selected so that the force of the hammer on the piston is sufficient to drive the piston downward and expel the water in chamber 242 through nozzle 244 as a pulsed jet.

ln operation, compressed air is continuously supplied to manifold 227, so that hammer 250 and piston 240 are cyclically operated, alternately allowing filling of chamber 242 and creation ofa pulsed jet. Water is continuously supplied to chamber 242, so that chamber 242 is always being filled during the upward motion of the piston when shuttle cock 302 has closed the bottom. A pulsed jet is formed each time the hammer strikes the piston on its downward movement. Bore 308 in piston 240 is provided to remove any air from chamber 242, since the presence of air would cushion the force applied to piston 240. As chamber 242 is filled with water, any air in chamber 242 is forced through bore 308 and check valve 310 to the exterior of the drill stem through line 312. Check valve 310 includes a floating piston 311, which operates to permit passage of air and water at the pressure in chamber 242. Upon impact of hammer 250 against piston 240, however, the sudden increase in pressure in chamber 242 operates on piston 311 to close check valve 310. Discharge openings 314 in casing 224 provide for communication between the compressed air manifold and the drill bit, such as to nozzle 134, shown in FIG. 1.

1t is claimed:

1. A rotary drilling bit for drilling wells of the type employed in petroleum exploration and production which comprises:

a bit body; a plurality' of leg members projecting downwardly from the bit body and spaced around a central axis of said bit body; a bearing member mounted on each of the leg members and having the axis thereof directed downwardly toward the central axis of the bit body; a conical bit element rotatably carried by each of the bearing members; and

means for forming pulsed jets of liquid comprising a nozzle block carried by the bit body having at least one opening therethrough and a bore therein transverse to the nozzle block opening;

piston means slidable within said nozzle block opening; valve means in said nozzle block transverse bore and defining with said piston means a compressible chamber in said nozzle block;

said valve means including a valve body, having a discharge opening adapted to be positioned in line with said nozzle block opening, said valve body being slidable within said transverse bore between a first valve position in which said valve body discharge opening is aligned with said nozzle block opening to provide a discharge path for said com pressible chamber and a second valve position in which the compressible chamber is closed;

liquid supply means for supplying liquid charge material to said chamber;

valve control means for controlling movement of said valve body between the first valve position and the second valve position;

bias means for normally urging said piston means from said nozzle block to enlarge said compressible chamber;

impelling means for rapidly acting on said piston means to compress said compressible chamber against the urging of said bias means and expel liquid charge material from said compressible chamber out said discharge opening as a pulsed liquid jet. including means for selectively controlling operation of said valve control means to selectively cause:

a. when the impelling means is not acting on said piston means to position said valve body in the second valve position and b. upon activation of said impelling means to compress said compressible chamber. to position said valve body in the first valve position, prior to actual expulsion of the liquid charge from the chamber; and

at least one nozzle arranged to direct said pulsed jet to a point outward of the conical elements and just below the lowermost surface of the conical elements.

2. A rotary' drilling apparatus for drilling a borehole comprising rotary drill means including a drill casing adapted for insertion into a borehole on an end of a drilling stem and at least one drilling bit connected to said casing; a nozzle passing from the interior of said casing downwardly and outwardly of said casing adjacent said drilling bit, said nozzle being directed outwardly of said drilling bit toward the periphery of said bottom surface ofthe borehole; and pulsed liquid jet forming means within said casing and coupled to said nozzle for forming a high velocity pulsed jet of liquid and expelling the pulsed jet of liquid through said nozzle to the bottom peripheral surface of a borehole into which the apparatus is inserted. thereby to cut out a ring on said bottom surface at the periphery and said drill means being arranged to cut said bottom surface of the borehole simultaneously with cutting of said ring by the pulsed liquid jet. said pulsed liquid jet forming means comprising means defining a compressible chamber having an inlet and an outlet; piston means for acting on said means defining the compressible charnber to compress said compressible chamber; means defining a first fluid flow path coupled to said compressible chamber inlet and including a valve for supplying liquid through said compressible chamber inlet to said compressible chamber while preventing flow of liquid from said compressible chamber through said compressible chamber inlet; and means defining a second fluid flow path coupling the compressible Chamber outlet with said nozzle for applying liquid under pressure to said nozzle. said nozzle having a tapered bore therethrough to increase the velocity and pressure of liquid passing therethrough from said compressible chamber, li l 

1. A rotary drilling bit for drilling wells of the type employed in petroleum exploration and production which comprises: a bit body; a plurality of leg members projecting downwardly from the bit body and spaced around a central axis of said bit body; a bearing member mounted on each of the leg members and having the axis thereof directed downwardly toward the central axis of the bit body; a conical bit element rotatably carried by each of the bearing members; and means for forming pulsed jets of liquid comprising a nozzle block carried by the bit body having at least one opening therethrough and a bore therein transverse to the nozzle block opening; piston means slidable within said nozzle block opening; valve means in said nozzle block transverse bore and defining with said piston means a compressible chamber in said nozzle block; said valve means including a valve body, having a discharge opening adapted to be positioned in line with said nozzle block opening, said valve body being slidable within said transverse bore between a first valve position in which said valve body discharge opening is aligned with said nozzle block opening to provide a discharge path for said compressible chamber and a second valve position in which the compressible chamber is closed; liquid supply means for supplying liquid charge material to said chamber; valve control means for controlling movement of said valve body between the first valve position and the second valve position; bias means for normally urging said piston means from said nozzle block to enlarge said compressible chamber; impelling means for rapidly acting on said piston means to compress said compressible chamber against the urging of said bias means and expel liquid charge material from said compressible chamber out said discharge opening as a pulsed liquid jet, including means for selectively controlling operation of said valve control means to selectively cause: a. when the impelling means is not acting on said piston means to position said valve body in the second valve position and b. upon activation of said impelling means to compress said compressible chamber, to position said valve body in the first valve position, prior to actual expulsion of the liquid charge from the chamber; and at least one nozzle arranged to direct said pulsed jet to a point outward of the conical elements and just below the lowermost surface of the conical elements.
 2. A rotary drilling apparatus for drilling a borehole comprising rotary drill means including a drill casing adapted for insertion into a borehole on an end of a drilling stem and at least one drilling bit connected to said casing; a nozzle passing from the interior of said casing downwardly and outwardly of said casing adjacent said drilling bit, said nozzle being directed outwardly of sAid drilling bit toward the periphery of said bottom surface of the borehole; and pulsed liquid jet forming means within said casing and coupled to said nozzle for forming a high velocity pulsed jet of liquid and expelling the pulsed jet of liquid through said nozzle to the bottom peripheral surface of a borehole into which the apparatus is inserted, thereby to cut out a ring on said bottom surface at the periphery and said drill means being arranged to cut said bottom surface of the borehole simultaneously with cutting of said ring by the pulsed liquid jet, said pulsed liquid jet forming means comprising means defining a compressible chamber having an inlet and an outlet; piston means for acting on said means defining the compressible chamber to compress said compressible chamber; means defining a first fluid flow path coupled to said compressible chamber inlet and including a valve for supplying liquid through said compressible chamber inlet to said compressible chamber while preventing flow of liquid from said compressible chamber through said compressible chamber inlet; and means defining a second fluid flow path coupling the compressible chamber outlet with said nozzle for applying liquid under pressure to said nozzle, said nozzle having a tapered bore therethrough to increase the velocity and pressure of liquid passing therethrough from said compressible chamber. 